An ink-jet recording apparatus has been known, which has a recording head for discharging ink as droplets onto a recording paper to print an image. The ink-jet recording apparatus is provided with at least an ink tank containing ink, to supply the ink from the ink tank to the recording head. The ink tank is provided with an ink chamber containing the ink, and an ink outlet for feeding the ink from the ink chamber out of the ink tank. The ink outlet consists of an ejection opening formed through a bottom wall of the ink chamber and an ejection tube connected to the ejection opening.
Because the ink is a consumable material, the ink tank is often formed as a cartridge that is removably attached to the ink-jet recording apparatus, so as to make it easy to supplement the ink-jet recording apparatus with the ink. Such a cartridge type ink tank, hereinafter called the ink cartridge, is replaced with another that is fully filled with the ink, when the ink contained in the ink cartridge is used up.
In order to notify the user of necessity to replace the ink cartridge, the ink-jet recording apparatus is provided with an ink run-out sensor for checking if the ink in the ink tank is used up. An example of such an ink run-out sensor is a photo sensor that detects the residual amount of the ink optically.
However, in many conventional cases, the ink remains a little in the ink cartridge even when the ink run-out sensor detects that the ink is used up. For the benefit of the user, it is desirable to reduce the residual ink in the used-up ink tank as much as possible. Various prior arts for reducing the final amount of residual ink have been suggested. For example, Japanese Laid-open Patent Application No. 1993-330076 discloses an ink cartridge having an ink chamber whose size is reduced from the top to the bottom so as to have a slope down to an ejection opening formed through the bottom wall. Thereby, the ink is let flow into the ejection opening.
Although the final amount of residual ink is reduced, this solution has a problem that the capacity of the ink chamber is reduced.